1. Field of the Invention
The present invention relates to display devices with optical sensors. In some embodiments, the optical sensors can be used to easily and reliably implement a touch screen function.
2. Description of the Related Art
In display devices, a touch screen function provides an intuitive interface through which a user can easily input information. Therefore, display devices with the touch screen function are very popular.
The touch screen function can be implemented via optical sensing. In such implementation, each pixel of the display device includes an optical sensor which senses a change in the amount of light incident on the optical sensor when the optical sensor is touched by a finger. The change in the amount of light is then converted to a voltage. Optical sensing is considered to be of interest mainly for small-size display devices based on polycrystalline silicon (p-Si) because in display devices based on polycrystalline silicon PIN diodes can be used which have superior photosensitivity.
However, when the touch screen function is implemented in a p-Si display device that supports an image scanning function, the pixel circuitry may become complicated and vulnerable to noise. In addition, as the resolution of the p-Si display device increases, the amount of data that needs to be processed may increase. As a result, the signal processing time of the display device may increase.
Furthermore, there is a need for large-size display devices based on amorphous silicon (a-Si) and having the touch screen function.